Arlon AD350A: High Frequency PTFE Laminate for Microwave Applications

There’s a specific category of PCB design where the usual laminate shortlist doesn’t cut it — high-power microwave circuits where the board itself has to handle serious thermal loads, maintain phase stability over a wide temperature range, and survive years of field operation without degrading. Low noise amplifiers, low noise blocks for satellite reception, bandpass filters, and directional couplers all fall into this category. For these applications, Arlon AD350A is one of the materials that comes up repeatedly in conversations between RF engineers who’ve had to solve this problem more than once.

This guide covers everything you need to know about Arlon AD350A: what it is, the full verified property set pulled directly from the datasheet, what makes it different from its predecessor and competitors, how to design with it, what to expect from the fabrication process, and where to find the technical resources you need. Whether you’re evaluating AD350A for the first time or troubleshooting a design that’s already using it, this is the reference you need.

What Is Arlon AD350A? Material Background and Development History

Arlon Electronic Materials developed the AD Series as a cost-optimised family of woven fiberglass-reinforced PTFE composite laminates for high-volume commercial wireless and microwave applications. Rogers Corporation acquired Arlon in 2015, and the AD Series materials — including Arlon PCB AD350A — continue under Rogers’ Advanced Electronics Solutions division with the original Arlon brand designations intact.

The “AD” prefix stands for Antenna Dielectric, though the AD350A’s application scope extends well beyond antenna work into power amplifiers, satellite components, and filtering networks. The “350” reflects a nominal dielectric constant of 3.50. The “A” suffix is a generational marker — AD350A was specifically redeveloped from the original AD350 to deliver three measurable improvements: higher thermal conductivity, lower thermal expansion, and better interlaminar and copper bond integrity.

That redevelopment history matters. The original AD350 had acceptable electrical properties but fell short in thermal management performance for the power levels being designed into modern LNA and power amplifier boards. The “A” generation addressed those gaps directly. Higher thermal conductivity means the substrate conducts heat away from active devices more efficiently. Lower CTE means less mechanical stress on solder joints and plated through-holes during power cycling and environmental temperature swings. Better copper bond integrity means the conductor-to-substrate adhesion holds up in high-power operation where thermal gradients across the board are significant.

The construction is a woven fiberglass-reinforced, ceramic-filled, PTFE-based composite. PTFE provides the inherently low-loss dielectric foundation. Woven fiberglass reinforcement controls X-Y dimensional stability. The ceramic filler drives the thermal conductivity improvement, lowers Z-axis CTE beyond what plain PTFE/glass achieves, and stabilises the dielectric constant over temperature.

Arlon AD350A Full Electrical Properties from the Datasheet

This is the verified property set from the AD350A datasheet — not estimated values, not inferred from related materials. These are the numbers the fab and design community actually work from.

Key Electrical Properties

Property	Value	Condition	Test Method
Dielectric Constant (Dk)	3.50 ±0.05	10 GHz, C23/50	IPC TM-650 2.5.5.5
Dissipation Factor (Df)	0.003	10 GHz, C23/50	IPC TM-650 2.5.5.5
Thermal Coefficient of εr	−55 ppm/°C	−10°C to +140°C	IPC TM-650 2.5.5.5
Volume Resistivity	1.2 × 10⁹ MΩ·cm	C96/35/90	IPC TM-650 2.5.17.1
Surface Resistivity	4.5 × 10⁷ MΩ	C96/35/90	IPC TM-650 2.5.17.1
Dielectric Breakdown	>45 kV	D48/50	ASTM D-149
Arc Resistance	>180 seconds	D48/50	IPC TM-650 2.5.1B
Copper Peel Strength (½ oz)	15 pli	A, TS	IPC TM-650 2.4.8
Copper Peel Strength (1 oz)	17 pli	A, TS	IPC TM-650 2.4.8

The Dk of 3.50 puts AD350A in a useful design position — higher than the 2.50–2.55 range of the AD250C/AD255C materials, which allows for more compact circuit geometries. A higher dielectric constant produces narrower 50Ω traces and physically smaller resonant structures, which is valuable when board real estate is constrained in satellite head-end assemblies or compact filter banks. The ±0.05 tolerance is well-controlled and consistent with what Rogers’ manufacturing infrastructure can hold reliably across production panels.

The dissipation factor of 0.003 at 10 GHz is moderate by PTFE standards — higher than the 0.0014 of the AD250C/AD255C materials but substantially lower than RO4350B’s 0.0037 and dramatically lower than standard FR4 (typically 0.018–0.024 at 10 GHz). For high-power designs, the loss tangent determines how much input power is converted to heat within the substrate itself. At 0.003, the dielectric contribution to insertion loss is manageable even at frequencies up to 18–20 GHz for moderate trace lengths.

The thermal coefficient of dielectric constant (TCεr) of −55 ppm/°C is a critical spec for phase-sensitive applications. It means the Dk decreases slightly as temperature increases, by approximately 55 parts per million per degree Celsius. For a transmission line in an LNB operating across −40°C to +85°C, this means the effective electrical length of a resonant structure changes with temperature — a fact that has to be budgeted into the design margin for bandpass filters where center frequency stability matters.

Why the Copper Peel Strength Numbers Matter

The peel strength values of 15 pli (½ oz copper) and 17 pli (1 oz copper) are higher than many competing PTFE laminates. Copper adhesion to PTFE is inherently challenging because of PTFE’s non-stick surface chemistry. The improved interlaminar and copper bond integrity in AD350A compared to the original AD350 directly shows up in these numbers. In high-power RF applications, copper traces that carry significant RF current experience thermal cycling stress at every power on/off cycle. Weak peel strength is a long-term delamination risk in power amplifier applications — it’s not a dramatic failure mode, but it’s one of the mechanisms behind gradual performance degradation over years of field operation.

Arlon AD350A Mechanical and Thermal Properties

Thermal and Dimensional Properties

Property	Value	Units	Condition	Test Method
CTE — X-axis	5	ppm/°C	0°C to 100°C	IPC TM-650 2.4.24 TMA
CTE — Y-axis	9	ppm/°C	0°C to 100°C	IPC TM-650 2.4.24 TMA
CTE — Z-axis	35	ppm/°C	0°C to 100°C	IPC TM-650 2.4.24 TMA
Thermal Conductivity	0.45	W/m·K	100°C	ASTM E-1225
Thermal Coefficient of Dk	−55	ppm/°C	−10°C to +140°C	IPC TM-650 2.5.5.5
Flammability	V-0	—	C48/23/50, E24/125	UL 94 / IPC TM-650 2.3.10

Mechanical Properties

Property	Value	Units	Condition	Test Method
Tensile Modulus	>700	kpsi	A, 23°C	ASTM D-638
Tensile Strength	>20	kpsi	A, 23°C	IPC TM-650 2.4.18
Compressive Modulus	>350	kpsi	A, 23°C	ASTM D-695
Flexural Modulus	>540	kpsi	A, 23°C	ASTM D-790
Specific Gravity	2.1	g/cm³	A, 23°C	ASTM D-792 Method A
Water Absorption	0.10	%	E1/105 + D24/23	IPC TM-650 2.6.2.2

Understanding the CTE Numbers

The X-axis CTE of 5 ppm/°C and Y-axis CTE of 9 ppm/°C are notably low — and notably asymmetric. This anisotropy is a characteristic of woven fiberglass-reinforced PTFE composites, where the weave pattern creates different stiffness in the two in-plane directions. The warp direction (typically X) has tighter fibre spacing and higher reinforcement density, producing lower CTE. The fill direction (Y) has slightly looser spacing, giving a higher CTE value.

For BGA package attachment and chip-scale package design, this asymmetry matters — the package CTE needs to be matched to the board CTE in both axes, not just nominally. Copper’s CTE is approximately 17 ppm/°C. The relatively low X/Y CTE values of AD350A compared to copper mean there’s still a CTE mismatch, but the Z-axis CTE of 35 ppm/°C is substantially lower than plain PTFE/glass materials, which typically run 150–200 ppm/°C in the Z-direction. That lower Z-axis CTE directly improves plated through-hole barrel reliability in high-temperature operating environments.

The thermal conductivity of 0.45 W/m·K is above average for PTFE-based laminates. Standard PTFE/glass composites typically measure 0.20–0.30 W/m·K. The ceramic filler in AD350A pushes this to 0.45 W/m·K, which is meaningful in high-power designs where the substrate has to conduct heat from active device mounting locations to the board edge or to a heatsink bonded to the back face. AD350A is also available bonded to heavy metal ground planes — aluminium, brass, or copper plate — which provides an integral heatsink and mechanical support platform for the most thermally demanding designs, such as high-power combiner amplifier modules.

The water absorption of 0.10% is higher than the AD250C/AD255C materials (<0.02–0.03%) — a relevant difference for outdoor applications where environmental humidity exposure is long-term. For indoor satellite and telecom equipment, 0.10% is typically acceptable. For designs installed in outdoor enclosures without perfect environmental sealing, it’s worth verifying the expected long-term humidity exposure against the operating frequency and loss budget.

Material Availability: Configurations and Ordering

AD350A is available in a specific set of configurations that cover the majority of high-power microwave PCB designs.

Standard Dielectric Thicknesses

AD350A is available in 0.010″ increments across the standard thickness range.

Thickness (inches)	Thickness (mm)	Typical Use Case
0.015″	0.381	Compact filters, thin substrates
0.020″	0.508	Moderate-power LNA circuits
0.025″	0.635	General microwave substrates
0.030″	0.762	Standard LNA/LNB boards
0.060″	1.524	High-power combiner amplifiers
0.062″	1.575	Power amplifier modules with heatsink bonding

Available master sheet sizes include 36″ × 48″ and 36″ × 72″ — the larger panel size is a notable benefit for antenna and combiner boards where high element or branch counts require large panel area.

Copper Foil Options

Foil Type	Weight	Notes
Electrodeposited (ED)	½ oz, 1 oz, 2 oz	Standard configuration
Rolled Copper	Available on request	Lower surface roughness for reduced skin effect loss at high frequencies
Heavy Metal Ground Plane	Aluminium, Brass, Copper plate	Integral heatsink — ideal for power modules

The availability of heavy metal ground plane bonding is one of AD350A’s differentiating configuration options. Bonding the laminate directly to an aluminium or copper base plate during manufacturing creates a rigid, thermally conductive assembly that eliminates the need to mount a separate heatsink after fabrication. For power amplifier modules in outdoor base station or satellite head-end enclosures, this approach simplifies assembly and improves thermal interface resistance compared to post-fabrication heatsink attachment.

Arlon AD350A vs. Competing RF Laminates

Understanding where AD350A sits in the competitive landscape helps explain when it should be selected over alternatives.

Material	Dk (10 GHz)	Df (10 GHz)	Z-CTE (ppm/°C)	Thermal Conductivity (W/m·K)	Primary Strength
Arlon AD350A	3.50 ±0.05	0.003	35	0.45	Thermal + compact geometry + PTH reliability
Arlon AD250C	2.50 ±0.04	0.0014	~45–50	0.42	Ultra-low loss, low PIM antenna work
Arlon AD255C	2.55 ±0.04	0.0014	~50	0.42	Low loss, compact antenna, low PIM
Rogers RO4350B	3.48 ±0.05	0.0037	46	0.69	FR4-compatible process, high thermal conductivity
Rogers RT/duroid 5880	2.20 ±0.02	0.0009	~237	0.20	Lowest loss, mmWave, aerospace
Taconic TLX-8	2.55 ±0.04	0.0019	~181	0.22	Low loss PTFE
Isola Astra MT77	3.00	0.0017	~46	0.49	Hydrocarbon, low loss, FR4-like process

AD350A vs. RO4350B: These two sit at essentially identical dielectric constants (3.50 vs. 3.48), making them direct design substitutes from an impedance standpoint. RO4350B wins on thermal conductivity (0.69 vs. 0.45 W/m·K) and on FR4-compatible processing — a significant manufacturing advantage. AD350A wins on Z-axis CTE (35 vs. 46 ppm/°C) and dissipation factor (0.003 vs. 0.0037). If your shop can process PTFE and the application demands lower loss and better PTH reliability over thermal cycling, AD350A is the stronger choice. If FR4-compatible processing and maximum thermal conductivity are the priority, RO4350B pulls ahead.

AD350A vs. AD250C/AD255C: These are not direct substitutes — they occupy different positions in the design hierarchy. AD250C/AD255C offer substantially lower Df (0.0014 vs. 0.003) and are the first choice for ultra-low-loss, low-PIM antenna and feed network work. AD350A’s higher Dk creates more compact circuit geometries and its improved thermal conductivity and heavy metal backing options make it the better choice for high-power active circuits. Many complete system designs use AD250C/AD255C for the antenna feed network and AD350A for the power amplifier or LNA module — choosing each material where its specific strengths are needed.

AD350A vs. RT/duroid 5880: RT/duroid 5880 offers far lower Df (0.0009) for the most demanding low-loss microwave applications but its Z-axis CTE of ~237 ppm/°C creates significant PTH reliability risk. AD350A’s Z-axis CTE of 35 ppm/°C is over six times lower, which is why engineers who need good loss performance and good PTH reliability over thermal cycling tend to favour AD350A over duroid for designs that will see field service in varying temperature environments.

Arlon AD350A PCB Design Considerations

Transmission Line Design and Impedance Planning

With Dk = 3.50, the characteristic impedance calculations for AD350A produce narrower traces than you’d get on the lower-Dk AD250C/AD255C materials. On a 0.030″ substrate with 1 oz copper, a 50Ω microstrip trace runs approximately 0.70–0.75 mm wide — narrow enough to make tight transitions and compact filter structures practical. Always run your impedance calculations with an electromagnetic field solver rather than closed-form equations at microwave frequencies. The anisotropic CTE values hint at the fact that the fibre weave geometry also slightly affects effective Dk values, particularly in the direction perpendicular to the weave.

When designing for high power, account for conductor loss carefully. Skin effect concentrates RF current at the copper surface, and the surface roughness of the copper foil contributes meaningfully to conductor loss above 5 GHz. If your operating frequency is above 5 GHz and insertion loss is tightly budgeted, specify rolled copper foil rather than standard ED foil — the smoother surface reduces skin-effect losses.

Layout Practices for High-Power Circuits

Ground plane continuity is more critical in high-power microwave designs on AD350A than in typical signal-level work. RF return currents concentrate immediately below the signal trace in a microstrip configuration — any gaps or slots in the ground plane below a high-power trace create local impedance discontinuities and can cause hot spots in the dielectric. Keep the ground plane continuous and uninterrupted beneath all high-current RF traces.

For designs using the metal-backed configuration, ensure that the thermal via strategy — if thermal vias are used — connects efficiently to the metal backing. The value of the aluminium or copper back plate as a heatsink depends on the thermal resistance from the device to the plate. Thin thermal vias with poor copper fill reduce the effective thermal path, offsetting the benefit of the metal backing. Work with your PCB manufacturer on the via fill strategy early in the design process.

Designing LNA and LNB Circuits on AD350A

Low noise amplifiers and low noise blocks are particularly well matched to AD350A’s property set. The relatively compact trace geometries at Dk = 3.50 keep matching network dimensions manageable. The improved copper peel strength reduces the risk of subtle adhesion issues that can degrade LNA noise figure over time through increased resistive losses at the copper-dielectric interface. The thermal conductivity advantage over plain PTFE/glass laminates helps manage the heat generated by the MMIC or discrete transistor even in small module footprints.

One design consideration specific to LNA work: the TCεr of −55 ppm/°C means resonant structures in input matching networks drift with temperature. For broadband LNA designs, this is typically within acceptable limits. For narrowband LNAs targeting a specific satellite downlink band with tight gain flatness requirements, temperature compensation of the matching network may be needed — or the match needs to be designed with enough bandwidth to accommodate the expected Dk shift across the operating temperature range.

Filter and Coupler Design on AD350A

Bandpass filters and directional couplers are classic applications for AD350A. The higher Dk compared to AD250C/AD255C allows more compact resonator dimensions, which is useful for multi-section filters with tight element pitch. The stable Dk versus frequency — which the AD350A datasheet graphs show remaining flat within ±2% from 0 to 30 GHz — means filter response shapes scale predictably with frequency and the fabricated filter center frequency matches the simulation closely.

For coupled-line couplers (branch line, rat race, Lange), the tight Dk tolerance of ±0.05 directly controls the coupling coefficient and impedance of the coupled sections. When the Dk varies across a panel, the coupling values shift, and the coupler’s directivity and insertion loss both move away from the designed values. AD350A’s controlled production Dk is therefore a yield-protection feature as much as a performance specification.

PTFE PCB Fabrication: What AD350A Requires

AD350A is compatible with the processing used for standard PTFE based printed circuit board substrates. That compatibility statement in the datasheet carries important practical implications — it assumes a shop that actually has PTFE processes, not FR4-only processes.

The specific requirements that separate PTFE fabrication from FR4 fabrication apply fully to AD350A. Drilling requires tuned parameters for PTFE’s soft, gummy cutting behaviour — lower spindle speeds, sharp carbide tooling, and properly managed chip load to avoid hole wall smearing. Standard FR4 drill parameters will leave poor hole wall quality that compromises copper plating adhesion.

Through-hole surface activation is mandatory. PTFE’s fluoropolymer surface won’t accept electroplated copper without surface treatment. Both sodium naphthalene chemical etch and CF4/O2 plasma etch approaches break up the fluorine-carbon bonds at the hole wall surface, creating adhesion sites for the copper seed layer. Skipping this step produces holes that appear plated but have inadequate adhesion — a failure mode that may not show up in incoming inspection but emerges as PTH delamination or opens during field thermal cycling.

Lamination for multilayer AD350A designs requires PTFE-compatible bonding films. Standard FR4 prepreg cures at incompatible temperatures and creates adhesion failures between PTFE and epoxy layers. Fluoropolymer bonding films — typically FEP or similar fluoropolymer adhesive films — are the correct choice for bonding AD350A cores in a multilayer stackup.

Typical Applications of Arlon AD350A

High-Power Amplifier Modules: AD350A’s combination of adequate Df, improved thermal conductivity, and metal backing option makes it a natural substrate for power amplifier boards where device junction temperatures must be managed. The metal backing eliminates the thermal interface resistance of a separate heatsink and provides mechanical rigidity for large module formats.

Low Noise Amplifiers (LNAs): LNA designs at C-band through Ku-band benefit from AD350A’s compact geometries, stable Dk, and strong copper adhesion. The material’s thermal stability ensures matching network performance is maintained over operating temperature ranges.

Low Noise Blocks (LNBs) for Satellite Reception: LNBs at Ku-band (10.7–12.75 GHz) and Ka-band (17.7–21.2 GHz) are high-volume commercial applications where AD350A’s performance/cost balance is a direct fit. Compact filter and matching network structures, stable Dk across the outdoor operating temperature range, and established supply chain from Rogers make it a production-ready choice.

Microwave Filters and Couplers: Bandpass filters, lowpass filters, branch-line couplers, and Wilkinson dividers in base station channel filter banks and antenna feed systems regularly use AD350A. The higher Dk compared to the AD255C family enables more compact element dimensions, which helps when fitting multi-section filters into the constrained mechanical envelopes of modern infrastructure hardware.

Radar Subsystems: Ground-based and airborne radar front-end circuits operating in S-band through X-band use AD350A for receive/transmit modules where thermal management and compact microstrip dimensions are both design priorities.

Useful Resources for Arlon AD350A

Resource	Description	Link
Rogers AD Series Datasheet (AD250C, AD255C, AD300D, AD350A)	Official Rogers datasheet with full properties table	rogerscorp.com
AD350A Original Datasheet PDF (Nanotech mirror)	Direct PDF of the original Arlon AD350A technical datasheet	nanotech.by/Arlon-PTFE-AD350A.pdf
UL Prospector AD350A Entry	Full mechanical, thermal, and electrical property database entry	ulprospector.com
Rogers MWI-2010 Impedance Calculator	Microstrip and stripline impedance calculator optimised for Rogers/Arlon materials	Rogers Calculator
Rogers Laminate Properties Tool	Interactive property filter and comparison for all Rogers and Arlon materials	Rogers Laminate Tool
Legacy Arlon AD Series Full PDF (Cirexx)	Original Arlon multi-product AD Series brochure with Dk vs. frequency graphs	cirexx.com/AD-Series.pdf
IPC TM-650 Test Methods Library	Full library of IPC test methods referenced in the AD350A property table	ipc.org
Knowde AD350 Material Listing	Material overview with properties and availability information	knowde.com

Arlon AD350A Frequently Asked Questions

Q1: What are the key differences between Arlon AD350A and the original AD350?

AD350A was specifically redeveloped from the original AD350 to address performance gaps in three areas: thermal conductivity, thermal expansion, and copper bond integrity. The “A” generation delivers higher thermal conductivity (enabling better heat rejection from active devices), lower Z-axis CTE (improving plated through-hole barrel reliability over thermal cycling), and improved interlaminar and copper peel strength (better adhesion and resistance to delamination in high-power, high-temperature operating conditions). The Dk and Df values remain consistent with the original AD350 spec at approximately 3.50 and 0.003 at 10 GHz.

Q2: Can AD350A be bonded to a metal ground plane, and what are the benefits?

Yes — AD350A is explicitly available bonded to heavy metal ground planes including aluminium, brass, or copper plate. This configuration provides an integral heatsink and mechanical support structure directly as part of the laminate assembly. The primary benefit is thermal: the metal backing provides a high-thermal-conductivity path from the substrate into the heatsink, with no additional thermal interface resistance from separate heatsink attachment hardware. It also stiffens the assembly against mechanical flex and vibration, which is valuable for outdoor power amplifier modules in infrastructure hardware.

Q3: How does AD350A’s dissipation factor compare to FR4, and does it matter at sub-6 GHz frequencies?

AD350A’s Df of 0.003 at 10 GHz compares to FR4’s typical Df of 0.018–0.024 at the same frequency — roughly 6–8 times lower. At sub-6 GHz frequencies, AD350A’s Df is even lower, closer to 0.002 at 2–3 GHz. For a passive filter or combiner network in a base station, the difference in insertion loss between AD350A and FR4 over a 100 mm trace at 3.5 GHz is meaningful — FR4 would contribute approximately 0.5–0.8 dB of dielectric loss while AD350A would contribute less than 0.1 dB. For a high-power transmit path where every tenth of a dB of loss is wasted output power, this difference directly affects system efficiency and thermal management requirements.

Q4: What PTFE-specific fabrication steps are absolutely required for AD350A?

Three steps are non-negotiable for reliable AD350A PCBs. First, drill parameter tuning — PTFE material requires lower spindle speeds and sharp tooling to avoid hole wall smearing and bell-mouthing that compromises plating adhesion. Second, through-hole surface activation — the fluoropolymer surface must be treated with sodium naphthalene chemical etch or CF4/O2 plasma before copper plating; without this step, copper plating adhesion is poor regardless of other process controls, leading to PTH barrel failures in service. Third, PTFE-compatible bonding films for multilayer assembly — standard FR4 prepreg is not compatible with PTFE lamination temperatures and creates adhesion failures at layer interfaces. A PCB shop that hasn’t processed PTFE-based materials before should not be attempting AD350A boards without process development work.

Q5: Is AD350A still available now that Arlon has been acquired by Rogers Corporation?

Yes. Rogers Corporation acquired Arlon in 2015 but has maintained the AD Series product line under the Arlon brand designation within Rogers’ Advanced Electronics Solutions division. AD350A is actively manufactured and available through Rogers and their authorised materials distributors. When ordering, request a material certificate to confirm the laminate meets the published AD350A datasheet specification. For high-volume programs, Rogers can discuss direct supply arrangements. For prototype and small-volume quantities, multiple authorised distributors carry stock. The Rogers online laminate properties tool lists AD350A alongside all current Rogers and Arlon materials, confirming its active production status.